Telephone-exchange system



June 9, 1925. 1,541,338

' G. R. MARTIN TELEPHONE EXCHANGE SYSTEM Filed Dec. 19, 1923 n m g/52 ffivenfor; GeorgeE/Var/M y My.

dune Q, 1925.,

in Ema lhli v A L GEORGE R. MARTIN, OF E! T GRANGE, NEW-J JERSEY, ASSIGNOB TO W'ESTERN ELEC- "IRIC COMPANY, T.I TCOBPO1't-ATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

Application filed Beceinoer 19, 1923.

To all 107mm it may, concern:

Be it known that I, Gnonsn R. lifnn'rin, citizen of the United States of America, residii'ig at East Orange, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Tele fihone-l lxcha-nge Systems, of which the follovi'ing is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems and particularly to methods of controlling the signaling of a called subscriber in such systems.

ii here machine switching offices and manual ofiices are both used in one local area, the manual. offices are provided with trunks incoming from the machine switching of [ices and with call indicators which may be associated with said incoming trunks to indicate the number of the subscriber with whom connection is desired. A number of incoming trunks will be located at one operators position and one call indicator, In order to associate a particular incoming; trunk with the common call indicator a key is provided, individual to each trunk.

Party lines are of two classes, those haring one per line and those having one jack for each station on the line. In order to signal the various parties on a party line having a jack for each station, the bells at the subscribers station are arranged to respond only to positive or only to negative ringing current and the ringers are connected either between the ring side of the line and ground or between the tip side of the line and ground. With the jack-perstation arrangement, the side of the line to which ringing current is applied may be determined by rerersing the connections of the line to two of the jacks. In some jackper-station ofiices, the selection of positive or negative current is determined by means oi a marginal relay in the trunk circuit controlled by special resistance on the sleeve of two of the jacks of the line. In some cases, however, the action of this marginal relay unreliable due to variations in the ground potential.

It is an object of the present invention to provide means for reliably controllii H h the lnno of rn aging current applied to a Serial No. 681,588.

subscribers line with the minimum labor on the partof the operator.

A feature of the invention lies in the provision of means for automatically select ing one type of ringing current when a call is completed, and means under the control of the operator for disabling this selecting means to send out another type of current.

A further feature of the invention lies in means under the control of the operator for releasing said disabling means when said disabling means has been operated in error.

These and other features of the invention will be more clearly understood from a consideration of the following description in connection with the drawings and appended claims:

The drawings show in diagrammatic form a calling subscribers line in a machine switching office with means for extending a connection from said subscribers line to an operators position in a manual o ifice and thence to a called partys station on a fourparty jaclI-per-station line. A trunk circuit at such operators position is shown in detail. The call indicator mechanism to which all the trunks at her station have access is merely suggested by the rectangle at the bottom of the sheet.

Reference is made to Patent 1,895,977, to F. A. Stearn and F. J. Scudder, issued November 1, 1921, for a description of the extension of a connection from a calling subscribers line to a district selector and the selection and setting of a subscribers register sender. Reference is also made to Patent lfltl hOS l, to A. E. Lundell and E. H. Clark, issued August 7,1923, for a description of the extension of a connection from a district selector to a manual oifice and the operation of. a call indicator at such manual oiiice. Although in the LundelLClark pat out the registrations are set up on the sender under the control of an operator, the action of the sender in extending a connection is the same as that of the sender set under the control of a callingsubscriber as described in the Stearn-Scudder patent.

In the drawings, it has been assumed that parties W and R on line 160 are signaled by means of positive ringing current and that parties M and J are signaled by negative ringing current; also that parties and J have their'ringers connected to the conductor 1-11 of the line 160 and parties It and M. have their ringers connected to conductor 14.0 of the line 160.

Suppose now that the subscriber at substation 100 desires to speak with the sub scriber at substation 101 which is designated on the line 160. In the assumption just made, this subscriber will be signaletl by positive ringing current applied to conductor 1 11.

The subscriber at substation 100 will remove his receiver from the switchhook whereupon line switch 102 will hunt for an idle district selector. As soon as an idle district selector 103 is found, the idle register sender 1041 will be selected and placed under the control of the calling subscriber. The subscriber now manipulates his dial to register on the sender the number of the wanted subscriber. hen the number has been completely registered the sender will proceed to control the selection of an idle oft-ice selector switch 105 by the district selector 103, and the selection of an idle trunk 150, 151 leading to a manual oflice by the office selector 105. These operations will take place substantially as set forth in the above enumerated patents to Stearn et al and Lundell et al.

lVhen connection is made with trunk 150, 151, a circuit is completed from battery right winding of relay 106, inner normal contact of relay 107, lower left winding of repeating coil 108, lower back contact of relay 109, conductor 151, thence through oliice selector 10.), district selector 103 and a relay (not shown) in sender 101, back through the district and officeselectors to conductor 150, upper back contact of relay 109, upper left winding of repeating coil 108, outer normal contact of relay 107, left winding of relay 106 to ground. The sender relay energizes in this circuit as a signal that connection has been completed to a. manual operators position and the sender apparatus prepares to send out the pulses to operate the call indicator. Relay 106 also energizes in'this circuit and closes a circuit from ground, front contactof relay 106, left back contact of relay 112, winding of relay 111, right back contact of relay 110 to battery. Relay 111 operates and closes a locking circuit for itself from battery at its outer right front contact through the winding of relay 1.11, left back contact of relay 112 to ground at the front contact of relay 106. The operation of relay 111 closes a circuit for lamp 113 extending from battery, througa lamp 113, resistance 11%, inner right front contact of relay 111 to ground. The illumination of lamp 113 informs the operator that a call is waiting on the corresponding trunk,

hen the operator notices that lamp 113 is lighted, she responds to the call by de pressing the assignment key 115 which is individual to trunk 150, 151. The depression of key 115 operates to associate the trunk with the call indicator mechanism. A circuit is closed from battery through the winding of a relay 152 in the call indicator mechanism, left back contact of re lay 117, left winding of relay 116, left front contact of relay 111, contact of key 115 to ground in the call indicator apparatus. Relay 116 operates and locks in a circuit from battery, winding of relay 152, left back contact of relay 117, both windings of relay 116 to ground at the inner right contact of relay 116. Relay 116 therefore locks independent of key 115, which restores as soon as it is released by the operator. Relay 116 also closes a circuit from battery, winding of relay 110 to ground at the outer right contact of relay 116. The operation of relay 110 closes a circuit from battery at the outer right front contact of relay 111 and inner left front contact of relay 110, winding of relay 118 to ground. Relay 118 operates and closes a circuit from battery at its inner right contact, winding of relay 109, left front contact of relay 116 to ground in the call indicator apparatus. Relay 105) operates and extends the trunk con ductors 150 and 151 to conductors 139 and 119, respectively, and thence to the call indicator apparatus. Relay 118 also closes a circuit through its winding and left front contact, winding of relay 112 to battery in which circuitrelay 112 operates. The operation of relay 109, opens the circuit of relay 106 and that relay deenergizes in turn causing the deenergization of relay 111. ith relay 110 operated and relay 111 decnergized, a circuit is closed for lamp 113, from battery, through lamp 113, resistance 111, inner right back contact of relay 111, outer left front contact of relay 110,'interrupter 137 to ground and lamp 113 Hashes to indicate that the call has been answered and the call indicator has been associated with. the trunk to which lamp 113 is individual. 7

The closure of the trunk to the call indicator ap iaratus initiates the operation of the sender to transmit code pulses, which pulses effect the setting of the call indicator to indicate the number of the wanted line. After the code impulses have all been sent in the manner described in the above mentioned patent to Lundell et al, a circuit is closed in the call indicator for relay 148 which opens the circuit of relay 100. Re lay 109 becomes deenergized, disconnects the trunk conductors 150 and 151 from the impulse leads 139 and 119 and connects them through to the left side of the repeating coil 108. flelay 106 is again energized, this time through line switch 102, and the calling subscribers substation, and closes a circuit from battery, winding of relay 112, left front contact of that relay, front con tact of relay 106 to ground. This circuit shunts relay 118 and that relay releases.

The operator observing the designation of the wanted line on the indicator lamps, seizes plug 120 of the trunk circuit which is identified by the flashing of assignment lamp 113 and inserts it in the jack 121 which corresponds to the called party V. The insertion of the plug in the jack com pletes a circuit from battery through the winding of relay 125, right back contact of relay 12 1-, winding of relay 123, sleeve of plug 120, sleeve of jack 121, winding of relay 122 to ground. Relay 123 operates in this circuit and closes a circuit from battery, winding of relay 127, right back contact of relay 128 and left back contact of relay 126 in parallel with the winding of relay 28, outer right front contact of relay 112, outer right back contact of relay 118, winding of relay 117, resistance 130 to ground at the lower front contact of relay Relays 127 and 117 energize in this circuit, relay 127 serving to connect ringing current over the ring of the plug and jack to conductor 1 11. Relay 117 opens the circuit of relay 116 to release the call indicater apparatus. The release of relay 116 also opens the circuit of relay 110 extinguishing lamp 113. Relay 125 also enerin'the circuit of relay 123 and connects positive ringing current from source 133 through its front contact, winding of relay 126, to the lower front contact of relay 127,

ring of plug 120 and jack 121 over conduc tor 111 to ground through the ringer 162. The called subscribers bell rings in this circuit but relay 126, which is marginal, does not operate. Then the called subscriber answers, a circuit is completed for relay 126 extending from source of ringing current 133, front contact of relay 125, winding of relay 126, lower front contact of relay 127, ring of plug 120 and jack 121 conductor 141. through the called subscribers subset, conductor 140, back to the tip of jack 121 and plug 120, upper front contact of relay 123 and upper front contact of relay 127 to ground. Relay 126 operates in this circuit and opens the shunt around the winding of relay 1.28. Relay 128 operates and closes a locking circuit for itself from battery, at its right front Contact, winding of relay 128 and thence as before traced to ground at the contact of relay 123. This locking circuit shunts relay 127 which relay dcenergizes and closes the called subscribers line through to the right windings of repeating coil 108, the circuit including supervisory relay 138. Relay 138 operates and closes a circuit for relay 107-fr0111 battery,

winding of relay 107, front contact of relay 138, left front contact of relay 128 to ground. Relay 107; operates in this circuit and reverses the current over the trunk 150, 151 for any desired purpose. The conversation may now proceed.

Vl hen conversation is completed, the called subscriber places his receiver on the switchhook and opens the circuit of relay 138. Relay 138 releases and opens the circ'uit of relay 107. Relay 107 becomes oleenergized and again reverses the direction of flow of current over the trunk conductors 150 and 151. When the calling subscriber hangs up and releases the switches, opening the trunk conductors 150 and 151, relay 106 deenergizes and opens the circuit of relay 112. During the time that relay 112 is energized, the disconnect signal lamp 129 is shunted by a circuit from battery, either through the winding of relay 127 and the back contacts of relays 128 and 126, or through the front contact and Winding of relay 128 to the front contact of relay 112 and thence to ground as previously traced. lVhen, however, relay 112 becomes deenergized, this short circuit is removed and lamp 129 is illuminated in a circuit from battery, through lamp 129, winding of relay 117, resistance 13-0, relay 123 to ground. The operator observing the illumination of lamp 129 knows that the connection is no longer desired and removes plug 120 from jack 121, whereupon relays 123, 125 and 117 release and lamp 129 is extinguished.

From the above it will be clear-that whenever a subscriber 1V or R on line160 is called, it is only necessary for the operator to plug into the corresponding jack and positive ringing current is automatically selected. The connection of the bell of the subscribers substation and the jack at the operators position taking care of the discrimination between parties 1V and R.

Suppose, however, that the subscriber at substation 100 had desired connection to the party M on line 160. The connection will proceed as before described until such time as the number is displayed on the call indicator. At this time, relays 109, 118, 112, 110 and 116 are operated. The operator observing that party M is wanted and know ing that party M requires negative ringing current operates key 161 which is also individual to trunk 150. 151. The oper: key 161 closes a circuit from battery, winding of relay 124:, contact of key 161 to ground. Relay 12l operates and locks in a circuit from battery tl'irough its winding and left front contacts, resistance 1'55, inner right front contact of relay 112 to ground. This circuit is independent of key 161 and that key restores as soon as released by the operator. The operation of relay 121. opens and lower front contact of lilti the circuit of relay 125 to disable the sclcction of positive ringing current and prepares a circuit for relay 123. When the plug 120 is inserted in jack 156 corresponding to party M, a circuit is completed from battery, through resistance 15?, right front contact ofrelay 124, winding of relay 123, sleeve of plug 120 and jack 156 to ground. Relay 123'operates and closes a circuit as before for relays 127 and 117. Since the circuit of relay 125 is open at the right contact of relay 12 1- a circuit may be traced from source of negative ringing current 158, back contact of relay 125, winding of relay 126, lower front contact of relay 127, ring of plug 120, ring of jack 156, conductor 140, through ringer of party M to ground. Party M is'signaled and when that party answers, relay 128 is operated and relay 127 released as before described. The release ofthe connection permits the release of relay 112 which opens the locking circuit of relay 1241 and returns that relay to the control of key 161.

From the foregoing it will be apparent that in calling parties M or J, which require negative ringing current it is only necessary for the operator to momentarily dcpress key 161 in order that the selection of positive ringing current may be disabled and that negative ringing current be applied to the called line.

It at any time before the plug 120 is inserted in a jack the operator realizes that she has erroneously operated key 161, the master ringing key 159, which is common to'all the trunks appearing at that position, may be operated. This connects battery through the contact of key 159, inner back contact of relay 117, right front contact of relay 124. resistance 155, inner right front contact of relay 112 to ground. This circuit shunts relay 124C and that relay releases restoring the circuit of relay 125. If, however, the plug has been inserted in the jack it must be withdrawn before the character of the ringing current can be corrected since the releasing circuit from key extends over the back contact of relay 117, which relay is operated upon the operation ot rclay 123, which in turn operates as soon as the plug is completely inserted in the jack.

To summarize, the circuits in accordance with this invention simplify the work necessary by a call indicator operator in that, for half the parties on party lines. it is not necessary for her to operate a ringing key and for the'other parties it is only necesr'or her to depress a key momentarily.

Although the circuit of the present inven tion has been described as a substitute for a circuit use in oflices equipped with marginal sleeve resistances where such marginal operation is unreliable, it is also well adapted for temporary use where the marmenses ginal sleeve resistances are to be installed eventually, since the amount of additional equipment is small, and the work of changing the trunks from one method of operation to the other is slight.

1V hatis claimed is:

1. In a telephone exchange system, calling subscribers lines, called subscribers lines each serving a plurality of subscribers substations, an operators position, a plurality of trunks at said operators position each terminating in a calling plug, means for extending a calling subscribers line to one of said trunks, a plurality of jacks at said operators position, each jack representing a called subscribers substation, signaling means at the several substations of each line adapted to be operated by dittcn ent characters of ringing current, means for generating said dilfcrcnt characters of ringing current, a relay operated in response to the insertion of a plug in a jack to select a particular character of ringing current, means to apply said current to said called line tooperate certain of said signaling means on that line, and a second relay under the control of said operator for opening the circuit of said first relay to apply a ditterent character of current to the called line to operate others of said signaling means on that line.

2. In a telephone exchange system, calling subscribers lines, called subscribers lines each serving a plurality of subscribers substations, an operators position, a plurality of trunks at said operators position each terminating in a calling plug, means for extending acalling subscribers line to one of said trunks, a plurality of jacks at said operators position, each jack representing a called subscribers substation, signaling means at the several substations of each line adapted to be operated by different characters of ringing current, means for generating said different characters of ringing current, a relay operated in response to the insertion of a plug in a jack to select a par-- ticular character of ringing current, means to apply said current to said called line to operate certain of said signaling means on that line, a key at said opcrators position, and a second relay controlled. thereby for opening the circuit of said first relay to apply a different character of current to the called line to operate others of said signaling means on that line.

3. In a telephone exchange system, (alling subscribers lines, called subscribers lines each serving a plurality of subscribers sub stations, an operators position, a plurality oftrunks at said operators position, each terminating in a calling plug, means for extending a calling subscribers line to one of said trunks, a plurality of jacks at said operators position, each ack representing a called subscribers substation, signaling means at the several substations of each line adapted to be operated by different characters of ringing current, means for generating said different characters of ringing current, a relay operated in response to the insertion of a plug in a jack to select a particular character of ringing current, means to apply said current to said called line to operate certain of said signaling means on that line, a key at said operators position, a second relay controlled thereby for opening the circuit of said first relay to apply a dilterent character of current to the called line to operate others of said signaling means on that line, and means to hold said relay operated as long as the connection remains established.

4:. In a telephone exchange system, calling subscribers lines, called subscribers lines each serving a plurality of subscribers substations, an operators position, a plurality of trunks at said operators position each terminating in a calling plug, means for extending a calling subscribers line to one oi said trunks, a plurality t jacks at said operators position, each jack representing a called subscribers substation, signaling means at the several substations of each line adapted to be operated by different characters of ringing current, means for generating said different characters of ringing current, a relay operated in response to the insertion of a plug in a jack to select a particular character of ringing current,

means to apply said current to said called line to operate certain of said signaling means on that line, a key at said operators position, a second relay controlled thereby for opening the circuit of said first relay to apply a different character of current to the called line to operate others of said signah ing means on that line, and means under the control of the operator for releasing said second relay prior to the insertion of said plug in a jack.

5. In a telephone exchange system, calling subscribers lines, called subscribers lines each serving a plurality of subscribers substations, an operators position, a plurality of trunks at said operators position each terminating in a calling plug, means for extending a calling subscribers line to one of said trunks, plurality of jacks at said operators position, each jack representing a called subscribers substation, signaling means at the several substations of each line adapted to be operated by different characters of ringing current, a relay operated in response to the insertion of a plug in a jack to select a particular character of ringing current, means to apply said current to said called line to operate certain of said signaling means on that line, a key at said operators position, a second relay controlled thereby for opening the circuit of said first relay to apply a different character of current to the called line to operate others of said signaling means on that line, means to hold said second relay operated as long as the connection remains established, and means under the control of the operator for releasing said second relay prior to the insertion of said plug in a jack.

In Witness whereof, I hereunto subscribe my name this 14: day of December A. D.,

GEORGE R. MARTIN. 

